Advances in minimally invasive surgical technology could dramatically increase the number of surgeries performed in a minimally invasive manner. Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. The average length of a hospital stay for a standard surgery may also be shortened significantly using minimally invasive surgical techniques. Thus, an increased adoption of minimally invasive techniques could save millions of hospital days, and millions of dollars annually in hospital residency costs alone. Patient recovery times, patient discomfort, surgical side effects, and time away from work may also be reduced with minimally invasive surgery.
The most common form of minimally invasive surgery may be endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient""s abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately xc2xd inch) incisions to provide entry ports for laparoscopic surgical instruments. The laparoscopic surgical instruments generally include a laparoscope (for viewing the surgical field) and working tools. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by an extension tube. As used herein, the term xe2x80x9cend effectorxe2x80x9d means the actual working part of the surgical instrument and can include clamps, graspers, scissors, staplers, and needle holders, for example. To perform surgical procedures, the surgeon passes these working tools or instruments through the cannula sleeves to an internal surgical site and manipulates them from outside the abdomen. The surgeon monitors the procedure by means of a monitor that displays an image of the surgical site taken from the laparoscope. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy and the like.
There are many disadvantages relating to current minimally invasive surgical (MIS) technology. For example, existing MIS instruments deny the surgeon the flexibility of tool placement found in open surgery. Most current laparoscopic tools have rigid shafts, so that it can be difficult to approach the worksite through the small incision. Additionally, the length and construction of many endoscopic instruments reduces the surgeon""s ability to feel forces exerted by tissues and organs on the end effector of the associated tool. The lack of dexterity and sensitivity of endoscopic tools is a major impediment to the expansion of minimally invasive surgery.
Minimally invasive telesurgical robotic systems are being developed to increase a surgeon""s dexterity when working within an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location. In a telesurgery system, the surgeon is often provided with an image of the surgical site at a computer workstation. While viewing a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices of the workstation. The master controls the motion of a servomechanically operated surgical instrument. During the surgical procedure, the telesurgical system can provide mechanical actuation and control of a variety of surgical instruments or tools having end effectors such as, e.g., tissue graspers, needle drivers, or the like, that perform various functions for the surgeon, e.g., holding or driving a needle, grasping a blood vessel, or dissecting tissue, or the like, in response to manipulation of the master control devices.
Some surgical tools employ a roll-pitch-yaw mechanism for providing three degrees of rotational movement to an end effector around three perpendicular axes. At about 90xc2x0 pitch, the yaw and roll rotational movements overlap, resulting in the loss of one degree of rotational movement.
The present invention is generally directed to robotic surgery methods, devices, and systems. The invention provides a minimally invasive surgical tool which operates with three degrees of rotational movement at about 90xc2x0 pitch. In particular, the surgical tool employs a roll-pitch-roll configuration in which an elongate shaft is rotatable in proximal roll, a wrist member is pivotally mounted on the working end of the elongate shaft to rotate in pitch, and an end effector is pivotally mounted on the wrist member to rotate in distal roll around the wrist axis of the wrist member. At about 90xc2x0 pitch, the wrist axis is generally perpendicular to the shaft axis of the elongate shaft. The proximal roll around the shaft axis and the distal roll around the wrist axis do not overlap. In some embodiments, a pulley and cable mechanism is used to rotate and actuate the end effector.
In some embodiments, the end effector can be bent back beyond 90xc2x0 pitch. The mechanism coupling the end effector to the working end of the elongate shaft allows the wrist member and end effector to bend back by an angle xcex8 of more than about 90xc2x0 from the forward position, desirably by more than about 120xc2x0, and more desirably by more than about 135xc2x0. The ability to operate the end effector at about 90xc2x0 pitch and to bend back the end effector renders the wrist mechanism more versatile and adaptable to accessing hard to reach locations, particularly with small entry points such as those involving spinal, neural, or rectal surgical sites. In specific embodiments, a pair of linking arms are pivotally connected between the working end and the wrist member to facilitate bend back pitching while maintaining the size of the tool to a sufficiently small size for minimally invasive surgical applications.
In accordance to an aspect of the present invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end and a shaft axis, and at least one linking arm having a proximal end and a distal end. The proximal end is pivotally mounted on the working end of the shaft to rotate around a first pitch axis which is nonparallel to the shaft axis. A wrist member has a proximal portion pivotally connected to the distal end of the linking arm to rotate around a second pitch axis which is nonparallel to the shaft axis. An end effector is pivotally mounted on a distal portion of the wrist member to rotate around a wrist axis of the wrist member. The wrist axis extends between the proximal portion and the distal portion of the wrist member. The elongate shaft is rotatable around the shaft axis.
In some embodiments, the first pitch axis and the second pitch axis are parallel, and are perpendicular to the shaft axis. A pair of linking arms are connected between the working end and the wrist member. The end effector includes an end effector support pivotally mounted on the distal portion of the wrist member to rotate around the wrist axis. The end effector includes at least one end effector link pivotally mounted on the end effector support to rotate around a pivot axis which is nonparallel to the wrist axis. The pivot axis may be perpendicular to the wrist axis. The end effector may include a pair of end effector links. The end effector links may be rotatable around the pivot axis to move toward and away from one another. The end effector links may be rotatable around the pivot axis to move together in the same direction. One of the end effector links may be fixed relative to the end effector support.
In accordance with another aspect of the invention, a minimally invasive surgical instrument comprises an elongate shaft having a working end and a proximal end. The elongate shaft has a shaft axis between the proximal end and the working end. A wrist member includes a wrist axis between a proximal portion and a distal portion. An end effector is pivotally mounted on the distal portion of the wrist member to rotate around the wrist axis. At least one linking member is rotatably coupled between the working end and the wrist member to permit rotation of the wrist member relative to the working end, from a forward position in which the wrist axis is oriented with the end effector at the distal portion pointing generally away from the proximal end of the elongate shaft, to a backward position in which the wrist axis is oriented with the end effector at the distal portion pointing generally toward the proximal end of the elongate shaft.
In accordance with another aspect of the present invention, a method of performing minimally invasive surgery in a body cavity of a patient comprises introducing an elongate shaft having a working end into the cavity. The elongate shaft has a proximal end and a shaft axis between the working end and the proximal end. A wrist member which is pivotally coupled with the working end is rotated relative to the working end. The wrist member having a wrist axis. The method further comprises rotating at least one of the elongate shaft around the shaft axis and an end effector pivotally mounted on the wrist member around the wrist axis to position the end effector at a desired location inside the cavity.
In some embodiments, the wrist member is rotated around a pitch axis which is perpendicular to at least one of the shaft axis and the wrist axis to change an angle between the wrist axis and the shaft axis. The wrist member is rotated relative to the working end until the wrist axis is approximately perpendicular to the shaft axis. The wrist member may be rotated relative to the working end from a forward position in which the wrist axis is oriented with the end effector pointing generally away from the proximal end of the elongate shaft, to a backward position in which the wrist axis is oriented with the end effector pointing generally toward the proximal end of the elongate shaft.